Congenital Diaphragmatic Hernia

Introduction & Embryology - Hernia Genesis

• CDH: Protrusion of abdominal viscera into thoracic cavity due to a congenital diaphragmatic defect.
• Embryology: Diaphragm develops from four main embryonic structures:
  • Septum transversum (forms central tendon)
  • Pleuroperitoneal membranes (fuse to close pleuroperitoneal canals)
  • Dorsal mesentery of esophagus (forms crura)
  • Muscular ingrowth from lateral body walls.
• Hernia Genesis: Primarily due to failure of fusion of the pleuroperitoneal membranes, usually posterolaterally.
• Critical Window: This developmental failure occurs around 8-10 weeks of gestation.

⭐ Failure of pleuroperitoneal membrane closure, most commonly posterolaterally, around 8-10 weeks gestation leads to CDH.

Types & Associated Anomalies - Defect Varieties

• Bochdalek Hernia (Posterolateral): 📌 BPM LLL (Bochdalek Postero-lateral, More common, Left, Lung hypoplasia)
  • Most common type (~85-90%).
  • Predominantly left-sided (~85% of Bochdalek cases).
  • Leads to pulmonary hypoplasia.
• Morgagni Hernia (Anteromedial/Retrosternal):
  • Less common (~2-5%).
  • Usually right-sided.
• Eventration of Diaphragm:
  • Abnormal elevation; intact but thinned diaphragm.
• Associated Anomalies (~30-50% cases):
  • Cardiac (e.g., VSD, ASD).
  • CNS (e.g., neural tube defects).
  • Renal, Skeletal.
  • Chromosomal (e.g., Trisomy 13, 18, 21).

⭐ Bochdalek hernia (posterolateral) is the most common type (~85-90%), predominantly on the left (~85% of Bochdalek cases).

Pathophysiology & Clinical Features - Breathing Battle

• Pathophysiology:
  • Abdominal viscera herniate into thorax → lung compression.
  • Leads to:
    • Pulmonary hypoplasia: ↓ alveoli, bronchioles, vasculature (often bilateral).
    • Persistent Pulmonary Hypertension (PPHN): ↑ pulmonary vascular resistance.
  • Surfactant deficiency common.
• Clinical Features:
  • Immediate/early severe respiratory distress: cyanosis, tachypnea, retractions.
  • Scaphoid abdomen (empty, concave).
  • Bowel sounds audible in chest.
  • Barrel-shaped chest.
  • Displaced heart sounds.

⭐ Key pathophysiological defects are pulmonary hypoplasia (often bilateral, though defect is unilateral) and persistent pulmonary hypertension (PPHN).

Diagnosis & Management - Spot, Stabilize, Sew

• Diagnosis (Spot)

  • Prenatal US: Polyhydramnios, mediastinal shift, bowel/liver in chest.
  • Postnatal: Resp. distress, scaphoid abdomen, ↓ breath sounds. CXR confirms.

• Management (Stabilize & Sew)

  • 📌 Intubate, NG/OG tube, Stabilize, Surgery (INSure Survival!)

  • ⭐ Immediate postnatal management: intubate, decompress stomach/bowel with NG/OG tube, and strictly avoid bag-mask ventilation.

  • Stabilize: Gentle vent; Target $PaCO_2$ 45-65 mmHg; PPHN (iNO, ECMO).
  • Surgical repair: After stabilization (24-72 hrs).

Prognosis & Complications - The Long Haul

• Survival: ~70-90% with modern neonatal care.
• Prognosis hinges on:
  • Pulmonary hypoplasia severity.
  • Associated anomalies.
  • Persistent pulmonary hypertension (PPHN).

⭐ Prenatally measured Lung-to-Head Ratio (LHR) and liver herniation ('liver-up') are critical prognostic indicators.

• Long-term sequelae:
  • Chronic lung disease, GERD.
  • Neurodevelopmental delay, hearing loss.
  • Recurrence, chest wall deformities (scoliosis/pectus).

High‑Yield Points - ⚡ Biggest Takeaways

• Bochdalek hernia (left posterolateral) is the most common CDH.
• Defect in pleuroperitoneal membrane closure is the cause.
• Pulmonary hypoplasia and pulmonary hypertension are critical determinants of survival.
• Presents with respiratory distress, scaphoid abdomen, and bowel sounds in chest at birth.
• Diagnosis: prenatal ultrasound or postnatal chest X-ray showing bowel in thorax.
• Management: Immediate intubation, gastric decompression, delayed surgical repair after stabilization.
• Associated anomalies, especially cardiac, are common and impact prognosis.